sbcl Log

The relevant instruction formats wrongly defined a fixed position for
the immediate byte which broke disassembly when a memory argument was
used.

Fix this by using a prefilter to read the immediate like most other
instructions do.

Refactor for more OAOO-ness: Drop the instruction formats that were
used only for these comparison instructions; instead use others that
are nearly identical. This forces more copy-and-paste in the printer
definitions, so instead abstract the generation of printer lists for
SSE instructions into a separate function and use that here.

* We still have BACKEND_PAGE_BYTES, which should be a conservative
over-approximation of the OS's page size.

* GENCGC_PAGE_BYTES is mostly replaced by GENCGC_CARD_BYTES, the
byte granularity at which we track writes to old generations.
While we're using mprotect-based write barriers, this should be
a multiple of BACKEND_PAGE_BYTES.

* GENCGC_ALLOC_GRANULARITY is the minimum size we attempt to make
each allocation region. Should be a multiple of GENCGC_CARD_BYTES.
While we have largeish cards, this shouldn't ever be an issue, but
it might if we ever go down to < 1k cards.

* GENCGC_RELEASE_GRANULARITY is the minimum size at which we release
address space to the OS. This should always be a multiple of
BACKEND_PAGE_BYTES.